Fluid brake system including a mechanical lock



March 1965 H. M. VALENTINE ETAL 3,173,726

FLUID BRAKE SYSTEM INCLUDING A MECHANICAL. LOCK Filed July 5, 1961 2 Sheets-Sheet l INV EN TORS Frank R. SchuberT Harry M Valentine BY 79W ATTORNEYS March 15, 1955 H. M. VALENTINE ETAL 3,173,726

FLUID BRAKE SYSTEM INCLUDING A MECHANICAL. LOCK Filed July 5, 1961 2 Sheets-Sheet 2 78 FIG. 3.

INVENTORS Frank R. Schubert Harry M Valentine ATTORNEYS United States Patent 016" 3,173,726 Patented Mar. 16, 1965 3,173,726 FLUID BRAKE SYSTEM INtZLUDiNG A MEHANCAL BECK Harry M. Valentine and Frank R. Schubert, Elyria, Ohio, assignors to Bendix-Westinghouse Automotive Air Brake (Iompany, Eiyria, Ghio, a corporation of Delaware Fiied duly 5, 1961, Ser. No. 121,970 29 Claims. (\Cl. 333-9) This invention relates to a brake mechanism for vehicles and more particularly to a safety brake mechanism for vehicles equipped with conventional air brake systems.

One of the principal objects of the present invention is to provide a compressed air safety brake system for vehicles which is so constituted as to automatically and mechanically hold the brakes in applied position in the event that the system pressure drops below a predetermined value.

Another object is to provide in a compressed air braking system, a novel arrangement whereby the brakes may be automatically applied and locked in such position in the event of failure of or serious reduction in pressure of the fluid pressure supply.

Still another object is to provide in a system of the above character, a novel arrangement wherein release of the brakes may not be effected until the system pressure rises to a predetermined value such that it would be safe for the vehicle to proceed.

A further object is to provide a system wherein the brakes may be applied and locked in applied position by a manually operated control, such an arrangement providing an efficient parking brake construction under the direct supervision of the operator.

Still another object is to provide in a safety brake construction of the foregoing type, a novel arrangement whereby the braking effect of the safety brakes may be supplemented by operation of the usual brake valve.

A further object resides in the provision of a novel combined service and emergency brake actuator which may be locked in brake applied position and which includes an efiiciently operable construction of relatively few parts so arranged as to occupy a minimum of space.

Other objects and novel features of the invention will appear more fully hereinafter from the following de tailed description when taken in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are utilized for purposes of illustration only and are not to be taken as a definition of the limits of the invention, reference being bad for this purpose to the appended claims.

Referring to the drawings wherein similar reference characters refer to similar parts throughout the several views:

FIG. 1 is a diagrammatic view partly in section of a safety brake system embodying the principles of the present invention;

FIG. 2 is an axial sectional view of the novel brake actuator which is preferably used in the system of FIG. 1, and

FIG. 3 is an enlarged transverse sectional view of a portion of the actuator of FIG. 2 illustrating the relationship of the brake locking rollers and the brake push rod.

Referring more particularly to FIG. 1, the safety brake system of the present invention is illustrated therein as including an emergency reservoir and a service reservoir 12 adapted to be supplied with compressed air from a suitable source by way of conduits 14 and 16 having one-way check valves 18 and 29 therein, the reservoirs being connected to a control valve 22 by conduits 2.4, 26

and 28, a conventional double check valve 30 being ineluded for ensuring a supply of compressed air from one of the reservoirs in the event of failure of the other. By means to be described more fully hereinafter, the control valve 22 is adapted to control the application of fluid pressure to and from a novel emergency and service brake actuator 32 by Way of conduits 34, 36 and 38, the construction of the actuator 32 being such that a brake application may be mechanically locked or released under certain conditions in the operation of the system.

Referring more particularly to FIG. 2, the novel actuator 32 includes an emergency portion 40 and a service portion 42, the former including casing parts 44 and 46 having the peripheral portion of an emergency diaphragm 43 clamped therebetween by a suitable clamp 50. Part 46 is connected with casing part 52 by a clamp 54 with the peripheral portion of a service diaphragm 56 therebetween, a suitable push plate 57 bearing against the diaphragm 56 through the action of a return spring 58 having its opposite end bearing against the end wall 60 of the actuator. It will be seen from F168. 1 and 2 that the emergency portion 40 includes an emergency chamber 62 which is connected with the conduit 36 by way of an opening 64 while the service portion 42 includes a service chamber 66 which is connected with the conduit 38 by way of an opening 68. In order to make the actuator 32 as short as possible, the casing parts 44 and 46 are tapered and the diaphragms 48 and 56 are arranged in nesting relationship with the service dia phragm 56 of larger effective area. As shown, a push rod 7% is secured to the push plate 57 and is slideable through a guide 72 carried by the end wall 60, the push rod being provided- With a recess for receiving the end of a brake applying rod '74. As' well understood by those skilled in the art, the opposite end of the brake rod '74 may be connected with the vehicle brake through a conventional slack adjuster or other type of brake arm.

With the above arrangement it will be understood that when fluid pressure is supplied to the emergency chamber 62, both diaphragms 48 and 56 will be moved to the right to efiect a brake application through corresponding movement of the push rod '75) and brake rod 74. Also, in the event that a leak occurs in the diaphragm t3, the brakes will nevertheless be applied by the fluid pressure passing from the chamber 62 to the chamber 66.

The present invention provides a novel arrangement for mechanically and automatically locking the actuator 32 in brake applied position and as shown includes a plurality of locking rollers 76 which are interposed between a cam ring 78 and the push rod and are normally urged into locking position by means of a spring 80. In this position, brake applying movement of the rod '70 to the right may take place. However, any movement of the rod 76 to the left, corresponding to brake releasing movement, is prevented since the locking rollers become firmly wedged between the ring 78 and the rod '70 through the action of the spring 30. Thus, after the brake has been applied, the locking rollers 76 prevent brake releasing movement of the rod 70.

Means are provided for maintaining the locking rollers 7e in released position and preferably such means is controlled by fluid pressure. As shown, a fluid pressure release means 82 includes a cylinder 84 in which a deformable annular piston 86 of suitable plastic material'is housed and positioned between an O-ring seal 88 and the rollers 76, the cylinder including a chamber 90 to which fluid pressure from conduit 34 may be conducted by way of opening 92 and ducts 9'4 and 96 formed in the end wall 60. Thus, when the chamber 90 is charged with fluid under pressure, piston 86 is effective to move the locking rollers as to the right against the tension of the spring 80 to relieve the locking effect of the rollers upon the push rod 70 and allow movement of the latter in opposite directions for brake application and release. On the other hand when the chamber 90 is exhausted, the spring 80*is eflective to move the rollers 86 into locking position and prevent any left hand movement of the push rod 70 as above described.

A novel arrangement including the control valve 22'is provided for controlling the operation of the actuator 32. As shown, such arrangement comprises a graduating type of manually controlled brake valve 08, of conventional constructionand a combined manual automatic control valve 100 which' may be constructed as shown in the copending application of Harry M. Valentine et al. Serial Number 108,882 filed May 5, 1961 now Patent No. 3,115,- 161 dated December 24, 1953 and owned by the same ass'ignee. Brake valve 98 is provided with an inlet constantly connected with these'rvice reservoir 12 by way of conduits 102 and 104, and is provided with a pair of outlets, one of which is connected with the control valve 22 by conduit 106 and the other of which is connected with the manual control valve 100 by conduit 108. The manual control valve 100 is provided with an inlet connected to the service reservoir 12'through conduits 110 and 104,

and'an outlet connected with the conduit 34 by a conduit 112. Valve 100 is provided with a manually operable control handle 114 which may be moved inwardly to connect conduits 110 and 112 and close the left end of conduit 108. Handle 114 may also be manually moved outwardly to interrupt the communication between conduits-110 and 112 and connect conduit 108 with the conduit 112. The valve 100 is also capable of automatically connecting the conduits 112 and 108 when the fluid pressure in the reservoir 12 drops to a predetermined low value of the order of 40 p.s.i. It will be understood that the'br'ake valve 98 is provided with the usual exhaust connection 116whieh normally connects the outlet conduits 106 and 108 with the atmosphere when the valve 98 is in the normal release position, Thus when the control valve 114 is manually or automatically moved to the position where conduits 112' and 108 are connected, conduits 112 and 34will be exhausted through the exhaust opening 116 when the valve- 98 occupies the normal position.

Control valve 22 comprises a-casing 118 having a cavity 120 at one end thereofconnected at all times with the reservoir conduit 28 through inlet port or opening 122, and having a control chamber 124 at the other end thereof connected by way of control port or opening 126 to the control'conduit 34. A step control piston 128 is mounted within the control chamber 124 and is provided with ahollow plunger 130 having a valve 132 at its free end adapted to contact and open a disk valve 134, the latter being normally urged to the closed position shown by means of a spring 136. An intermediate portion of the plunger 130 is formed as a valve 138 adapted to close upon a seat 140 when the piston 128 moves to the left. In the position illustrated, fluid pressure in the control chamber 124 is eflective to move the control piston to the right against the tension of spring 142 to open valve 138 and connect the conduit 106 with both the conduits 36 and 38 by way of opening 144 and a hollow bore 146 in the plunger 130, the latter communicating with outlet port or opening 148 and port or opening 150 which'are respectively connected with the conduits 36 and 38.

With the parts in the position shown in FIGS. 1 and 2, the manual control valve 100 occupies the in or release position where fluid pressure from the reservoir 12 is conducted tOthe conduits 112 and 34 to maintain the control effect since the left end thereof is closed at the valve 100. Fluid pressure from conduit 106 however is con ducted to both the conduits 36 and 38 by way of opening 144, past open valve 138, to bore 145 and from the latter to opening 148 by Way of open valve 132, and to opening 150 through holes 152 in the plunger 130. Charging of conduit 36 will conduct fluid pressure to the emergency chamber 62 while charging of the conduit 38 will conduct fiuid pressure to'the service chamber 66. Since the emer-' gency diaphragm 48 is thereby subjected to equal pressures on opposite sides, any Wear on this diaphragm is greatly minimized. The simultaneous application of equal pressures to the chambers 62 and 66 will result in a service application of the brake through movement or the service diaphragm 56, the push rod 70 and the brake rod'74 to the right. Release of the brake is accomplished by allowing the brake valve 98 to returnto its normal inactive position to exhaust the chambers 62 and 66 to atmosphere through the connections heretofore described, and by way of the conduit 106 and the brake valve exhaust 116.

In the event that it is desired to operate the actuator 32 as a parking brake it is only necessary for the operator to manually move the handle 114 of the valve to its out or parking position to shut off the conduit 110 and connect conduits 112 and 108. Since the latter conduit is connected with the exhaust opening 116 of the brake valve 98 it will beunderstood that conduits 112 and 34 will also be exhausted. Exhausting of conduit 34 will exhaust the lock release means 82 so that the locking rollers will prevent movement of the push rod '70 to the left while permitting movement thereof to the right. Exhausting of the control chamber 124 of the control valve 22 will enable movement of the piston 128 toward the left to close valves 132 and 138 and open valve 134. Opening of the latter valve will serve to charge the emergency chamber 62 of the actuator 32 by way of emergency reservoir 10, conduit 28, opening 122, chamber 120, opening 148 and conduit 36 in order to effect a brake application through movement of the diaphragms 48 and 56 in unison, along with the brake operating parts associated therewith. It will be understood that such parking brake application will be maintained in a locked condition by the action of the locking rollers 76 even though the pressure of the supply reservoir may later be reduced to Zero through leakage or other failure.

It will be understood that in the event the supply pressure available in reservoir 12 drops to a value of the order of 40 p.s.i., the valve 100 will automatically operate in the same manner as if the operator had moved the handle 114 outwardly to the above described parking position. Under these conditions precisely the same brake application as above described would occur, which application would be locked in the applied position.

In the event that a service brake application is made while the valve 100 is in the above described parking or emergency position, with the handle 114 in its out position, fluid pressure will be delivered to the lock releasing means 82 through conduit 108, manual control valve 100,v

conduit 112 and conduit 34. Fluid pressure will also be conducted through the conduit 106 to the opening 144 of the control valve 22. Flow of such pressure through the control valve will at first be prevented by the closed valve 138. Howeven'as soon as the pressure within the control chamber 124 due to the charging of conduit 34 has attained a value such that piston 128 moves the valve 138 to open position, fluid pressure will be conducted to the service-chamber 66 by way of bore 146, opening 150 and conduit 38. In this manner, a service application of the brake chamber 32 may be made which will override the emergency or parking application.

When the above described service application is released by allowing the brake valve 98 to return to the normal release position, some compressed air may be trapped within the service chamber 66 as the valve 138 is moved to its closed position. Such trapped air will have the effect of increasing the emergency application by an amount equal to the difference in areas of the service and emergency diaphragms multiplied by the pressure trapped between them. This trapped pressure may be minimized by including a choke of conventional design in the opening 126 in order to retard the release of fluid pressure from the chamber 124.

In order to release the parking brakes, the handle 114 of the manually controlled valve 106 is moved to the in or release position in order to charge the control chamber 124 and the lock releasing means 82 through conduits 112 and 34. As soon as the control valve 22 returns to the position shown, the emergency chamber 62 will be exhausted by way of conduit 36, opening 148, open valve 132, bore 146, opening 152, opening 144, conduit 106 and the brake valve exhaust 116, the opening 144 of the control valve 22 thus serving as an exhaust port. Even though the cylinder 90 of the lock releasing means 82 is charged with fluid pressure through the conduit 34, this action will be insuflicient to release the locking rollers 76 from their wedging and locking engagement with the cam ring 78 and the push rod 70. Accordingly, the brake rod 74 will remain in its applied and locked position. This locked condition may be overcome by effecting a heavy service application of the actuator 32 suflicient to move the push rod 7% forwardly slightly in order to assist the piston 86 in unlocking the rollers 76. This action is accomplished by merely operating the brake valve 98 to charge the emergency and service chambers 62 and 66 a suflicient amount through conduits 36 and 38 as heretofore described.

In the event that the brake actuator 32 has been automatically applied through a drop in system pressure, the brake application may be unlocked and released in the manner just described, as soon as the fluid pressure has built up to a value in excess of 40 p.s.i.

From the foregoing, it will be readily understood that the present invention provides a highly eflicient safety brake mechanism which is automatically applied and mechanically held in applied position in the event that the system pressure drops to a predetermined value such that it would be unsafe to operate the vehicle. The construction is also such that the safety brake may be used for parking purposes by merely manually operating the valve 190 to its park position. In either case, the brakes may be readily unlocked and released by operation of the valve 100 to the release position combined with a heavy service application of the conventional brake valve,

The conical arrangement of the emergency and service portions of the brake actuator materially shortens the over-all length of the actuator, thus enabling installation on vehicles where space for accommodating brake actuators is at a premium. The double diaphragm construction and the system connections also provide a high degree of safety, inasmuch as during a service application, the pressures on opposite sides of the emergency diaphragm are balanced to minimize wear thereof. Also, in the event that the emergency diaphragm fails for any reason, the fluid pressure will be effective upon the service diaphragm to provide eflicient braking.

While the invention has been shown and described herein with considerable particularity, it will be understood by those skilled in the art that various modifications may be made therein without departing from the spirit of the invention. Reference will therefor be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

l. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means for releasing said brake locking means, a brake valve having an inlet, an outlet and an exhaust, a

rst connection between the brake valve inlet and source,

a second connection between the brake valve outlet and actuator and including a fluid pressure operated control valve responsive to fluid pressure from said source for movement to one position to open said second connection and for movement to a second position to close said second connection and connect said source directly with said actuator, and means including a manually operable control valve interconnected between said source, said brake valve outlet, said release means and said first named control valve, and movable to a first position to connect said release rneans wtih said source and to connect said first named control valve with said source whereby the latter valve is moved to said one position, and movable to a second position to exhaust said release means and move said first name control valve to said second position.

2. A fluid pressure safety brake system according to claim 1 wherein said manually operable control valve is automatically movable from said first to said second position when the pressure at said source drops to a predetermined value.

3. A fluid pressure safety brake system according to claim 1 wherein said actuator includes a pair of diaphragrns defining an emergency chamber at one side of one diaphragm and a service chamber between the diaphragms and said second connection includes a pair of conduits respectively connected with said chambers and said fluid pressure operated control valve so that both conduits are charged with fluid pressure when said last named control valve occupies said one position and said brake valve is operated to connect said source and the second connection.

4. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means for releasing said brake locking means, and means for controlling the application of fluid pressure to and from said actuator and to and from said release means, comprising a fluid pressure operated control valve, first conduit means connecting said control valve and actuator, second conduit means connecting said control valve and source, said second conduit means having a brake valve in series therein, third conduit means directly connecting said control valve and source, said control valve including a pressure responsive element movable in one direction in response to fluid pressure to connect said first and second conduit means and movable in the other direction in response to release of fluid pressure to disconnect said first and second conduit means and to connect said third conduit means with said actuator, and a manually operable control valve movable to one position to conduct fluid pressure from said source to said release means and to said pressure responsive element to respectively actuate the former and to effect movement of the latter in said one direction, and movable to another position to release fluid pressure from said pressure responsive element and from said release means.

5. A fluid pressure safety brake system according to claim 4 wherein said manually operable control valve is automatically operable from said one to said another position when the pressure at said source drops to a predetermined value.

6. A fluid pressure safety brake system according to claim 4 wherein said actuator includes a pair of diaphragms defining an emergency chamber at one side of one diaphragm and a service chamber between the diaphragms, and said first conduit means include a pair of conduits so that both conduits may be charged with fluid pressure when said pressure responsive element is moved in said one direction and said brake valve is operated.

7. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means for releasing said brake locking means,

means including a brake valve having a connection with said source and actuator for charging the latter with fluid pressure to effect a service brake application, means including a manually operable valve movable to one position for simultaneously opening said connection and charging said release means with fluid pressure and movable to a second position for releasing fluid pressure from said release means, for directly connecting said actuator and said source, and for closing said connection.

8. A fluid pressure safety brake system according to claim 7 wherein said manually operable valve is automatically operable'from said one to said second position when the pressure at said source drops to a predetermined value.

9. A fluid pressure safety brake system according to claim 7 wherein said actuator includes a pair of diaphragms defining an emergency chamber at one side of one diaphragm and a service chamber between the diaphragms, and said connection includes a pair of conduits respectively connected with said chambers and both conduits connected with said brake valve so that both conduits are charged with fluid pressure when said brake valve is operated.

10. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means for releasing said brake locking means, and means including a manually operable control valve movable in one direction to connect said actuator with said source and to connect said release means with the atmosphere, and movable in another direction to connect said actuator with the atmosphere and to connect said release means with said source, said means also including a fluid pressure operated control valve having a pressure responsive element movable in one direction in response to fluid pressure to connect said actuator with the atmosphere and movable in another direction in response to release of fluid pressure to disconnect said atmospheric connection to the actuator and connect thev latter with the source, means including a conduit connecting said manually operable control valve with said pressure responsive element to control the application of fluid pressure to and from said element in accordance with the movements of said manually operable valve and a brake valve having an inlet connected with said source and having an outlet connected with said manually operable control valve and said actuator and operable at will to connect the actuator and release means with the source when said manually operable control valve is moved in said one direction.

11. A fluid pressure safety brake system according to claim 10 wherein said manually operable control valve is automatically movable to connect said conduit with the atmosphere when the pressure at said source drops to a predetermined value. 7

12. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, spring-applied brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means fior releasing said brakelocking means, means for controlling the application of fluid pressure to and from said actuator and to and from said release means comprising, a fluid pressure operated control valve having a pressure responsive element movable in one direction inresponse to fluid pressure to connect the actuator with the atmosphere and movable in the oppositedirection in response to release of fluid pressure to disconnect said atmospheric connection to the actuator and connect the latter With said source, means including a manually operable control valve movable to one position to simultaneously connect said source with said pressure responsive element and said release means and movable to another position to connect said element and release means with the atmosphere, and a brake valve claim 12 wherein said manually operable control valveis automatically movable to said another position when the pressure at said source drops to a predetermined pressure.

14. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, spring-applied brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means for releasing said brake locking means, and means for controlling the application of fluid pressure to and from said actuator and to and from said release means comprising, a manually operable valve, a first conduit connecting said valve and source, a second conduit connecting said valve and release means, said valve being movable to one position to connect said first and second conduits to apply fluid pressure to said release means and being movable to a second position to disconnect said first and second conduits and to connect said second conduit with the atmosphere to exhaust fluid pressure from said release means, valve means movable to one position to connect said source and actuator and movable to another position to disconnect said source from the actuator and connect the latter with the atmosphere, a pressure responsive element for controlling the movements of said valve means, a third conduit for subjecting said pressure responsive element at all times to the pressure in said second conduit and a brake valve having an inlet connected with said source and having an outlet connected with said manually operable valve and said actuator and operable at will to connect said second conduit and actuator with said source when said manually operable valve occupies said second position.

15. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, spring-applied brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means for releasing said brake locking means, and means for controlling the application of fluid pressure to and from said actuator and to and from said release means comprising, a manually operable valve, a first conduit connecting said valve and source, a

second conduit connecting said valve and release means,

said valve being movable toone position to connect said first and second conduits to apply fluid pressure to said release means and being movable to a second position to disconnect said first and second conduits and to connect said second conduit with the atmosphere to exhaust fluid pressure from said release means, valve means including a casing having a control port, an inlet port, an outlet port and an exhaust port, first conduit means connecting said inlet port with said first conduit, second conduit means connecting said control port with said second conduit, and third conduit means connecting said outlet port with said actuator, said valve means including a valve movable to one position for connecting said inlet and outlet ports and movable to another position to disconnect the inlet port from the outlet port and connect the latter with the exhaust port, means within the casing responsive to fluid pressure at said control port for moving said last named valve to said positions and a brake valve having an inlet connected with'said source and having an outlet connected with said manually operable valve and said actuator and operable at will to connect said second conduit and actuator with said source when said manually operable valve occupies said second position.

16. A brake system according to claim 15 wherein the last named means includes a movable plunger having a pressure responsive part subjected to fluid pressure at said control PC1110]: moving said plunger in one direction,

and a spring for moving said plunger in another direction.

17. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, said actuator comprising a housing having a pair of cup-shaped diaphragms therein, one diaphragm defining a first pressure chamber between one side thereof and one end wall of the housing, and both diaphragms defining a second pressure chamber therebetween, the cross sectional area of said one diaphragm being less than the other diaphragm, resilient means interposed between the other diaphragm and the other end wall of the housing for normally maintaining the central portions of the diaphragms in contacting relationship and with a part of the central portion of said one diaphragm in engagement with said one end wall, a brake rod operatively connected with the other diaphragm and extending through said other end wall, spring-applied brake locking means in said housing for locking said rod against movement toward said one end Wall, fluid pressure operated release means for releasing said brake locking means, valve means for controlling the application of fluid pressure to and from said first pressure chamber and to and from said release means, said valve means including a manually operable member movable to one position to connect said source with said release means and to connect said first pressure chamber with the atmosphere, said manually operable member being movable to another position to connect said release means ith the atmosphere and connect said first pressure chamber with the source, and means including a brake valve for controlling the application of fluid pressure to and from said second pressure chamber.

18. A fluid ressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, a spring-applied brake locking means for locking said actuator in a brake applied position, fluid pressure operated release means for releasing said brake locking means, and valve means for controlling the application of fluid pressure to and from said actuator and to and from said release means, said valve means including a manually operable member movable to one position to connect said source with said release means and to connect said actuator with the atmosphere, said manually operable member being movable to another position to connect said release means with the atmosphere and connect said actuator with the source, and a brake valve having an inlet connected with said source and having an outlet connected with said valve means and said actuator and operable at will to connect said source with said release means and actuator when said manually operable member occupies said another position.

19. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, said actuator having first and second flexible diaphragms therein, said first diaphragm having a cross sectional area greater than that of said second diaphragm, a brake rod operatively connected with the first diaphragm, the space between said diaphragms defining a service chamber, and the space on the opposite side of the second diaphragm from the first diaphragm defining an emergency chamber, spring-applied locking means for locking said rod in brake applied position, fluid pressure operated release means for releasing said brake locking means, and means for controlling the application of fluid pressure to and from said service and emergency chambers and to and from said release means comprising, a fluid pressure operated control valve having a pressure responsive element movable in one direction in response to fluid pressure to connect the emergency chamber with the atmosphere and movable in the opposite direction in response to release of fluid pressure to disconnect said atmospheric connection to the emergency chamber and connect the latter with said source, means including a manually operable control valve movable to one position to simultaneously connect said source with said pressure responsive element and said release means so that the emergency chamber is connected with the atmosphere and the release means is charged with fluid pressure, said manually operable control valve being movable to another position to connect said element and release means with the atmosphere so that the emergency chamber is charged with fluid pressure from said source and the release means is connected with the atmosphere, and means including a brake valve for controlling the application of fluid pressure to said service chamber and for applying fluid pressure to said release means when said manually operable control valve is moved to said another position.

20. A fluid pressure safety brake system having a source of fluid pressure, a fluid pressure actuator for applying a vehicle brake, said actuator comprising a housing having opposed end walls, said housing having a pair of diaphragm therein, one diaphragm defining a first pressure chamber between one side thereof and one end wall of the housing, and both diaphragms defining a second pressure chamber therebetween, the cross sectional area of said one diaphragm being less than that of the other diaphragm, resilient means interposed between the other dia phragm and the other end wall of the housing for normally urging said diaphragms toward said one end Wall, a brake rod operatively connected with the other diaphragm and extending through said other end Wall, springapplied brake locking means in said housing for locking said rod against movement toward said one end Wall, fluid pres sure operated release means for releasing said brake looking means, valve means for controlling the application of fluid pressure to and from said first pressure chamber and to and from said release means, said valve means including a manually operable member movable to one position to connect said source with said release means and to connect said first pressure chamber with the atmosphere, said manually operable member being movable to another position to connect said release means with the atmosphere and connect said first pressur chamber with the source, and means including a brake valve for con trolling the application of fluid pressure to and from said second pressure chamber and for applying fluid pressure to said release means when said manually operable member is moved to said another position.

References fiited by the Examiner UNITED STATES PATENTS 

18. A FLUID PRESSURE SAFETY BRAKE SYSTEM HAVING A SOURCE OF FLUID PRESSURE, A FLUID PRESSURE ACTUATOR FOR APPLYING A VEHICLE BRAKE, A SPRING-APPLING BRAKE LOCKING MEANS FOR LOCKING SAID ACTUATOR IN A BRAKE APPLIED POSITION, FLUID PRESSURE OPERATED RELEASE MEANS FOR RELEASING SAID BRAKE LOCKING MEANS, AND VALVE MEANS FOR CONTROLLING THE APPLICATION OF FLUID PRESSURE TO AND FROM SAID ACTUATOR AND TO AND FROM SAID RELEASE MEANS, SAID VALVE MEANS INCLUDING A MANUALLY OPERABLE MEMBER MOVABLE TO ONE POSITION TO CONNECT SAID SOURCE WITH SAID RELEASE MEANS AND TO CONNECT SAID ACTUATOR WITH THE ATMOSPHERE, SAID MANUALLY OPERABLE MEMBER BEING MOVABLE TO ANOTHER POSITION TO CONNECT SAID RELEASE MEANS WITH THE ATMOSPHERE AND CONNECT SAID ACTUATOR WITH THE SOURCE, AND A BRAKE VALVE HAVING AN INLET CONNECTED WITH SAID SOURCE AND HAVING AN OUTLET CONNECTED WITH SAID VALVE MEANS AND SAID ACTUATOR AND OPERABLE AT WILL TO CONNECT SAID SOURCE WITH SAID RELEASE MEANS AND ACTUATOR WHEN SAID MANUALLY OPERABLE MEMBER OCCUPIES SAID ANOTHER POSITION. 